BLUE-GRAY GNATCATCHER, Polioptila C/Erulea, Char. Male: above, bluish gray, darker on head, paler on rumpj forehead and line over the eye black; beneath, pale bluish white; wings dusky; tail longer than the body, the outer feathers partly white. FeŽ male : similar to the male, but lacking the black on head. Length 4}i to 5 inches. Nest. A graceful, cup-shaped structure, saddled on limb of a tree 15 or 20 feet frora the ground; composed of felted plant fibre ornamented externally with lichens and lined with feathers. Eggs. 3-5; bluish white, speckled with bright brown; 0.55 X 0.45. But for the length of the tail, this would rank among the raost diminutive of birds. It is a very dexterous, lively insect- hunter, and keeps commonly in the tops of taU trees; its motions are rapid and incessant, appearing always in quest of its prey, darting from bough to bough with hanging wings and elevated tail, uttering only at times a feeble song of tsee tsee tsee, scarcely louder than the squeak of a mouse. It arrives in the State of Pennsylvania frora the South about the middle of April, and seldom passes to the north of the States of New York and Ohio, though others, following the course of the large rivers, penŽ etrate into Kentucky, Indiana, and Arkansas. Its first visits are paid to the blooming willows along the borders of waterŽ courses, and besides other small insects it now preys on the troublesome mosquitoes. About the beginning of May it forms its nest, which is usually fixed among twigs, at the height of 10, or sometimes even 50, feet from the ground, near the summit